Build merged apexkeys.txt/apkcerts.txt by partition.

Propagate partition tag data to apexkeys.txt and
apkcerts.txt so that merge_target_files.py can build
merged versions of these files by filtering the
framework files for framework partitions and filtering
the vendor files for vendor partitions.

Bug: 138942268
Change-Id: Ic3226728e97dae84d38ec230ccc86d1b124bea94
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index 5b7c2ac..783d63c 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -1082,7 +1082,8 @@
         r'public_key="(?P<PAYLOAD_PUBLIC_KEY>.*)"\s+'
         r'private_key="(?P<PAYLOAD_PRIVATE_KEY>.*)"\s+'
         r'container_certificate="(?P<CONTAINER_CERT>.*)"\s+'
-        r'container_private_key="(?P<CONTAINER_PRIVATE_KEY>.*)"$',
+        r'container_private_key="(?P<CONTAINER_PRIVATE_KEY>.*)"\s+'
+        r'partition="(?P<PARTITION>.*)"$',
         line)
     if not matches:
       continue